Hi again, here is a version that corrects the bug addressed by lmb: from random import randint from random import choice from os import getenv

Hi again, here is a version that corrects the bug addressed by lmb: from random import randint from random import choice from os import getenv from subprocess import call from sys import argv if len(argv) > 1: # get network interface from cmdline parameter intf = argv[1] else: # get network interface from ENVIRONMENT variables intf = getenv('INTERFACE', '') if intf: # generate random mac address r = lambda: randint(0,255) # Universally or Locally Administered Bit and Individual/Group Bit # See http://packetsdropped.wordpress.com/2011/01/13/ # mac-address-universally-or-locally-administered-bit-and-individualgroup-bit/ sbyte = choice(['%02X' % i for i in range(255) \ if bin(i)[-2] == '0' and \ bin(i)[-1] == '0']) randmac = sbyte + ':%02X:%02X:%02X:%02X:%02X' % (r(),r(),r(),r(),r()) # change mac address call(["ifconfig", "%s hw ether %s" % (intf, randmac)]) else: print "Couldn't determine network interface"